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Title: FREQUENCY DISTRIBUTION ANALYSIS OF BIMONTHLY GUAYULE LATEX YIELD FOR SELECTING OPTIMAL HARVEST DATES

Author
item Nakayama, Francis
item COFFELT, TERRY
item VINYARD, STEPHEN
item LEAKE, GREGORY
item CLARK, AMY

Submitted to: Association for the Advancement of Industrial Crops Conference
Publication Type: Abstract Only
Publication Acceptance Date: 8/12/2002
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Because guayule (Parthenium argentatum, Gray) is a perennial plant, harvesting for latex could conceivably be feasible throughout the year. Reports show that the rubber content increases during the cooler months, but this observation cannot be used as a guide for the optimum harvest period. Intuition would lead to the conclusion that harvest during the fall-winter months would be preferable to the summer months, but no evidence is available to support this type of harvesting scheme. The objective of this study was to apply the frequency distribution technique for the latex content data collected on a bimonthly basis to improve estimating harvesting times. Previously seasonal variations in latex content were noted, but the statistics used did not provide clear-cut differences that could be used to make recommendations on the optimal harvest period. A three-year data set was used that included latex analysis for three guayule lines sampled bimonthly. The years were separated into three separate groups and the bimonthly samples divided within each year. In addition, the latex contents for each sampling date for each line were arbitrarily categorized as either high or low and the frequencies of such designations were noted to characterize the harvest date for each of the plant lines. The frequency distribution was then tested by appropriate statistical analysis. Contingency table analyses indicate the appropriateness of the frequency distribution approach applied for the data set. The analysis indicated that the frequencies of high versus low yields are significantly dependent on the month of the year at the P<0.0001. Thus, the frequency tables developed showed clearly that the months for latex harvest for Arizona are through the November and succeeding January through March periods. The May through July harvest period will have the lowest latex yields.